77007ad950
This patch performs some additional restructuring of the manual,
specifically in the User Guide. In detail:
- Rename 'Daily use' to 'General Buildroot usage'
- Move chapters 'make tips', 'Eclipse integration', and 'Advanced usage' as
sections under the 'General Buildroot usage' chapter.
- Rename 'Details on Buildroot configuration' into 'Buildroot configuration'
- Rework the 'Customization' section as follows:
- Move the short section on debugging the external toolchain wrapper into
the rest of the explanation on external toolchains.
- Remove the now redundant section on toolchains, as this is already
explained in much more detail in the 'Buildroot configuration' chapter.
- Move the sections on busybox/uclibc/kernel configuration from chapter
'Customization' into a separate chapter 'Configuration of other
components'.
- Rename the remaining part of the original 'Customization' chapter into
'Project-specific customization' and fold it together with the next
chapter 'Storing the configuration'
- Remove the chapter 'Going further in Buildroot innards' thanks to:
- Moving the chapter 'How Buildroot works' to the Developer guide.
- Moving the 'Advanced Buildroot usage' section to the 'General Buildroot
usage' chapter.
- Remove the chapter 'Hacking Buildroot' by:
- Adding a reference to adding packages to the 'Project-specific
customizations' chapter
- Leaving out the explicit reference to creating board support, as this is
part of the previous chapter already, so an extra reference is
redundant.
Signed-off-by: Thomas De Schampheleire <thomas.de.schampheleire@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
153 lines
7.1 KiB
Plaintext
153 lines
7.1 KiB
Plaintext
// -*- mode:doc; -*-
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// vim: set syntax=asciidoc:
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[[customize-store-basics]]
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=== Basics for storing the configuration
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When you have a buildroot configuration that you are satisfied with and
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you want to share it with others, put it under revision control or move
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on to a different buildroot project, you need to store the configuration
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so it can be rebuilt later. The configuration that needs to be stored
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consists of the buildroot configuration, the configuration files for
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packages that you use (kernel, busybox, uClibc, ...), and your rootfs
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modifications.
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[[customize-store-buildroot-config]]
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==== Buildroot configuration
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For storing the buildroot configuration itself, buildroot offers the
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following command: +make savedefconfig+.
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This strips the buildroot configuration down by removing configuration
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options that are at their default value. The result is stored in a file
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called +defconfig+. If you want to save it in another place, change
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the +BR2_DEFCONFIG+ option, or call make with +make savedefconfig
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BR2_DEFCONFIG=<path-to-defconfig>+. The usual place is
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+configs/<boardname>_defconfig+. The configuration can then be rebuilt by
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running +make <boardname>_defconfig+.
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Alternatively, you can copy the file to any other place and rebuild with
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+make defconfig BR2_DEFCONFIG=<path-to-defconfig-file>+.
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[[customize-store-package-config]]
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==== Other package configuration
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The configuration files for busybox, the linux kernel, barebox and
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uClibc should be stored as well if changed. For each of these, a
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buildroot configuration option exists to point to an input
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configuration file, e.g. +BR2_LINUX_KERNEL_CUSTOM_CONFIG_FILE+. To
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save their configuration, set those configuration options to a path
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outside your output directory,
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e.g. +board/<manufacturer>/<boardname>/linux.config+. Then, copy the
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configuration files to that path.
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Make sure that you create a configuration file 'before' changing
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the +BR2_LINUX_KERNEL_CUSTOM_CONFIG_FILE+ etc. options. Otherwise,
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buildroot will try to access this config file, which doesn't exist
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yet, and will fail. You can create the configuration file by running
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+make linux-menuconfig+ etc.
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Buildroot provides a few helper targets to make the saving of
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configuration files easier.
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* +make linux-update-defconfig+ saves the linux configuration to the
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path specified by +BR2_LINUX_KERNEL_CUSTOM_CONFIG_FILE+. It
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simplifies the config file by removing default values. However,
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this only works with kernels starting from 2.6.33. For earlier
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kernels, use +make linux-update-config+.
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* +make busybox-update-config+ saves the busybox configuration to the
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path specified by +BR2_PACKAGE_BUSYBOX_CONFIG+.
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* +make uclibc-update-config+ saves the uClibc configuration to the
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path specified by +BR2_UCLIBC_CONFIG+.
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* +make barebox-update-defconfig+ saves the barebox configuration to the
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path specified by +BR2_TARGET_BAREBOX_CUSTOM_CONFIG_FILE+.
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* For at91bootstrap3, no helper exists so you have to copy the config
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file manually to +BR2_TARGET_AT91BOOTSTRAP3_CUSTOM_CONFIG_FILE+.
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[[customize-store-board-support]]
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=== Creating your own board support
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Creating your own board support in Buildroot allows users of a
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particular hardware platform to easily build a system that is known to
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work.
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To do so, you need to create a normal Buildroot configuration that
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builds a basic system for the hardware: toolchain, kernel, bootloader,
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filesystem and a simple BusyBox-only userspace. No specific package
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should be selected: the configuration should be as minimal as
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possible, and should only build a working basic BusyBox system for the
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target platform. You can of course use more complicated configurations
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for your internal projects, but the Buildroot project will only
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integrate basic board configurations. This is because package
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selections are highly application-specific.
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Once you have a known working configuration, run +make
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savedefconfig+. This will generate a minimal +defconfig+ file at the
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root of the Buildroot source tree. Move this file into the +configs/+
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directory, and rename it +<boardname>_defconfig+.
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It is recommended to use as much as possible upstream versions of the
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Linux kernel and bootloaders, and to use as much as possible default
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kernel and bootloader configurations. If they are incorrect for your
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board, or no default exists, we encourage you to send fixes to the
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corresponding upstream projects.
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However, in the mean time, you may want to store kernel or bootloader
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configuration or patches specific to your target platform. To do so,
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create a directory +board/<manufacturer>+ and a subdirectory
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+board/<manufacturer>/<boardname>+. You can then store your patches
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and configurations in these directories, and reference them from the main
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Buildroot configuration.
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=== Step-by-step instructions for storing configuration
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To store the configuration for a specific product, device or
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application, it is advisable to use the same conventions as for the
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board support: put the buildroot defconfig in the +configs+ directory,
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and any other files in a subdirectory of the +boards+ directory. This
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section gives step-by-step instructions about how to do that. Of course,
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you can skip the steps that are not relevant for your use case.
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1. +make menuconfig+ to configure toolchain, packages and kernel.
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1. +make linux-menuconfig+ to update the kernel config, similar for
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other configuration.
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1. +mkdir -p board/<manufacturer>/<boardname>+
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1. Set the following options to +board/<manufacturer>/<boardname>/<package>.config+
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(as far as they are relevant):
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* +BR2_LINUX_KERNEL_CUSTOM_CONFIG_FILE+
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* +BR2_PACKAGE_BUSYBOX_CONFIG+
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* +BR2_UCLIBC_CONFIG+
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* +BR2_TARGET_AT91BOOTSTRAP3_CUSTOM_CONFIG_FILE+
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* +BR2_TARGET_BAREBOX_CUSTOM_CONFIG_FILE+
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1. Write the configuration files:
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* +make linux-update-defconfig+
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* +make busybox-update-config+
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* +make uclibc-update-config+
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* +cp <output>/build/at91bootstrap3-*/.config board/<manufacturer>/<boardname>/at91bootstrap3.config+
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* +make barebox-update-defconfig+
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1. Create +board/<manufacturer>/<boardname>/fs-overlay/+ and fill it
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with additional files you need on your rootfs, e.g.
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+board/<manufacturer>/<boardname>/fs-overlay/etc/inittab+.
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Set +BR2_ROOTFS_OVERLAY+
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to +board/<manufacturer>/<boardname>/fs-overlay+.
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1. Create a post-build script
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+board/<manufacturer>/<boardname>/post-build.sh+. Set
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+BR2_ROOTFS_POST_BUILD_SCRIPT+ to
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+board/<manufacturer>/<boardname>/post-build.sh+
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1. If additional setuid permissions have to be set or device nodes have
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to be created, create +board/<manufacturer>/<boardname>/device_table.txt+
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and add that path to +BR2_ROOTFS_DEVICE_TABLE+.
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1. +make savedefconfig+ to save the buildroot configuration.
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1. +cp defconfig configs/<boardname>_defconfig+
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1. To add patches to the linux build, set +BR2_LINUX_KERNEL_PATCH+ to
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+board/<manufacturer>/<boardname>/patches/linux/+ and add your
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patches in that directory. Each patch should be called
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+linux-<num>-<description>.patch+. Similar for U-Boot, barebox,
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at91bootstrap and at91bootstrap3.
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1. If you need modifications to other packages, or if you need to add
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packages, do that directly in the +packages/+ directory, following the
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instructions in xref:adding-packages[].
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